1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive pre-computing seek parameters for a continuation track and a next command to facilitate continuing a read-ahead or aborting the read-ahead.
2. Description of the Prior Art
It is known to abort the read-ahead operation of a current read command in order to enhance a rotational position optimization (RPO) algorithm. The RPO algorithm will compute an “abort window” within which the read-ahead operation should be aborted in order for the head to reach the target track ahead of the target sector for the next command. If the abort window is missed, the seek for the next command is executed at the end of the read-ahead operation without gaining any improvement from the RPO algorithm.
It is desirable to seek the head to the target track for the new command as soon as possible after the head enters the abort window so that the head can reach the target track in time to perform a pre-read operation for the next command. Any delay in reaching the target track of the next command will effectively truncate the pre-read operation. In addition, a read-ahead for a current read command may extend through to a continuation track requiring a seek to the continuation track. However, the latency in pre-computing whether the head will reach the track boundary during the read command may delay detecting the abort window or cause it to be missed altogether thereby reducing the benefit of the RPO algorithm.
There is, therefore, a need to abort read-ahead operations soon after the head enters the abort window in order to maximize the pre-read operation for the next command while allowing a read-ahead operation of the current command to extend through to a continuation track.